1. Field of the Invention and Related Art Statement:
The present invention relates to a sheet guide apparatus suitable for use in a copying machine a facsimile machine, a printer, etc., and more specifically to a sheet guide apparatus for guiding each of sheets delivered from a fixing apparatus.
FIG. 8 shows a conventional example of this type of apparatus. There is first provided a fixing apparatus 102 having a structure of the type that a rotatable pressure roller 101 is upwardly pressed against a fixing roller 100 driven and rotated by an unillustrated drive unit. At the fixing apparatus 102 having such a structure, each of sheets 103 delivered from an unillustrated photosensitive drum is drawn in between the fixing roller 100 and the pressure roller 101 both of which are being rotated. At this time, the sheet 103 is delivered to a sheet delivery side in a state in which a printed face 103a with a toner image transferred thereon is being kept upward. Therefore, the printed face 103a is pressed against the fixing roller 100 by the pressure roller 101. As a consequence, the toner image is fixed on the sheet 103 owing to the heat produced by the fixing roller 100.
Then, a scraper 104 is provided on the sheet delivery side of the fixing apparatus 102 such that the distal end thereof is held in contact with an outer peripheral surface of the fixing roller 100. Thus, the sheet 103, which is discharged or delivered from the fixing apparatus 102 and which would otherwise be wound on the fixing roller 100, is scraped from the fixing roller 100 by means of the scraper 104. The sheet 103 thus scraped from the fixing roller 100 is guided between a pair of sheet delivery rollers 106 by a sheet delivery guide plate 105 provided on the sheet delivery side of the fixing apparatus 102 so as to be delivered, so that the sheet 103 is introduced into a sheet receiving unit 107 disposed below the sheet delivery rollers 106.
On the other hand, the sheets 103 thus introduced into the sheet receiving unit 107 are superposed on each other in a state in which each printed face 103 is being kept upward. Thus, when it is desired to print the sheets 103 with pages marked thereon, they are piled up on the sheet receiving unit 107 in reversed page order. Therefore, there is a demand for the delivery of the sheets 103 to the sheet receiving unit 107 in a state in which each printed face 103a is being kept downward with a view to superpose the sheets 103 on each other in page order. In order to meet this demand, a sheet changeover plate 108 is provided vertically and turnably on the sheet delivery side of the sheet delivery rollers 106 in the apparatus shown in FIG. 8. There is defined, in an upper portion of the changeover plate 108, a sheet delivery passage 110 adapted to reverse each of the sheets 103 delivered to the sheet delivery rollers 106 into an U-shape for thereby introducing the same into a sheet delivery tray 109 provided above a casing. Accordingly, each of the sheets 103 is selectively delivered to the sheet receiving unit 107 or the sheet delivery tray 109 above the casing according to angular positions of the changeover plate 108, and the sheets 103 are superposed on each other in page order within the sheet delivery tray 109.
A description will next be made of problems in the device referred to above. The sheet delivery guide plate 105 and the pair of sheet delivery rollers 106 are provided between the fixing apparatus 102 and the sheet receiving unit 107 or the sheet delivery passage 110. The conventional apparatus is therefore accompanied by the drawback that the dimension from the fixing apparatus 102 to the entrance of the sheet receiving unit 107 or the sheet delivery passage 110 is increased to produce dimensional enlargement of the sheet guide apparatus and to increase the number of components. In particular, it will be extremely convenient because the dimensional enlargement of the sheet guide apparatus causes machines such as copying machines in which the sheet guide apparatus is employed to be large in size.
In addition, components required to guide and carry each of the sheets 103 are essential for the delivery of the sheets 103. However, they can jam the sheets 103. The provision of such components is therefore accompanied by the drawback that the sheets 103 are jammed in the sheet delivery guide plate 105 or between the sheet delivery rollers 106.
The conventional apparatus is further provided with an unillustrated cleaner for removing any toner adhered to the fixing roller 100. However, there are some cases where the toner adhered to the fixing roller 100 cannot completely be removed according to the type of the cleaner. As a consequence, the remaining toner may be adhered to the pressure roller 101. In this case, the adhesion of the toner thereto results in the drawback that the reverse side of each sheet 103 is stained with the toner.